1. Field of the Invention
The present invention relates to improvements in bottle capping machines or bottle filling and capping machines to improve the efficiency and reliability of handling plastic bottles which have become a very common container for beverages and, to some extent, other liquids. More particularly, the invention relates to improvements particularly suited for plastic bottles with a lifter ring on the neck of the bottle and pre-threaded screw caps. As shown in FIG. 1 of the drawings, the lifter ring 12 is shown as the peripheral lip immediately below the threads 14 at the cap position on the bottle 10.
2. Description of the Known Art
In processing screw cap threaded containers through a known type of filling and/or capping machine (such as shown, for example, in U.S. Pat. No. 4,295,320 or U.S. Pat. No. 4,658,565, both patents hereby expressly incorporated by reference), it has been found to be necessary to prevent the spinning capping head that applies the screw cap from also rapidly spinning the bottle; such spinning of the bottle can have a very deleterious effect on the operation of the machine as the bottles pass through at a high rate of speed, often 100 bottles per minute or more. Various expedients have been employed to prevent spinning of the bottle as the screw cap is rotated on the threaded bottle neck and firmly seated with a desired torque. A very common expedient has been to provide knife elements or pin elements which penetrate the bottom edge of the lifter ring of the plastic bottle. While the reliability of such a technique is less than desirable and has the disadvantage that it inevitably leaves a mark on the bottle, it has been accepted in the industry.
U.S. Pat. No. 5,826,400, issued to Martin et al. on Oct. 27, 1998 discloses a plastic bottle spinning restraint for a capping machine which is also hereby incorporated by reference in its entirety. This patent application is directed to a method for holding the petaloid shape at the bottom of a bottle to be capped so that the bottle will not spin during the capping procedure. Modifications in the amount of plastic utilized by the bottling companies has affected the ability of the bottle to support itself to allow this machine to properly restrain the bottle during the capping procedure. Therefore, a new method for holding the bottle during the capping procedure is needed.
Referring to FIG. 1, it will be noted that bottle capping machine environment is shown representing a typical bottling machine employed for capping (or filling and capping) petaloid plastic bottles which uses a rotational movement of the bottle under a spinning capping head that is concurrently rotated. While the bottom shape for holding a plastic bottle is shown, the knife apparatus for engaging the cap ring on the neck of the bottle to prevent rotation (as in U.S. Pat. No. 4,658,565) is not shown. Such previously known apparatus should in any event be disabled or removed from the apparatus in order to employ Applicants' invention. The advantages of removing or disabling the apparatus employing bottle-piercing knives which catch and engage the bottle under the neck ring can better be understood by a brief description of such apparatus and its function. For the knife type apparatus, a substantial amount of downward pressure on the top of the bottle, e.g. 20-50 pounds, is necessary to force the underneath side of the bottle neck ring into the pins or knives to prevent rotation of the bottle. This downward force must be induced through the closure threads to the bottle threads, and this method has two detrimental effects. First, the friction resulting from the thread to thread contact creates a variance in the application torque. The application torque being the summation of the sealing friction and thread friction. Secondly, the knives can create a sharp burr on the edge of the neck ring because of their necessary indentation in the plastic. If the knife edges are not in excellent condition, they will peel the plastic from underneath the neck ring which results in the accumulation of undesirable shavings around the area of the capping operation. Often the knife edges will produce a sharp bur under the neck ring which can cause injury to the consumer of the product when the closure is removed. Even a slight injury which breaks the skin of the consumer is of potential concern.
The rotation restraint system shown in FIG. 1 is simple and usable on virtually all strong plastic bottles which have petaloid bases. A reduction in the amount of plastic in the bottles has made this system unusable for new lower material bottle designs. However, this does provide a good basis for understanding the environment for the present invention. As seen in FIG. 1, the major feature of the prior art is the provision of a rotational base plate 20 having plurality of sets of fingers 22 in a petaloid configuration arranged in a nest residing below the primary surface 24 of table 26 and configured to accept the bottom 16 of the particular size and shape of petaloid bottle being processed. It should be noted that as to most of the elements and parts of a capping machine (excluding the previous form of bottle anti-rotation device) their function and, in most cases, their structure will not be changed. Elements retaining their usual function include rotating center unit 30, upper stationary guide 40, lower stationary guide 50, upper rotating receiver 60, and mid-level rotating receiver 70. It will be appreciated that the particular configuration of these elements will change if, and when, there is any significant change in the size or shape of the bottle being processed. In FIG. 1, the apparatus required to transport bottles to and convey bottles away from table 26 has been omitted in order to better show important features. Also much of the capping and/or filling structure and the cap supply means has been omitted. Although capping machines are known in which the table, such as table 26, turns in a counterclockwise direction, table 26 in FIG. 1 and the other rotating elements moving therewith turn in a clockwise or leftward direction as indicated by arrow 31. Each bottle, such as uncapped bottle 18, is first positioned by a star wheel or other conveyor mechanism and received in recess 21 of rotating receiver 20 and is guided and maintained in vertical position by recesses 62 and 72. In FIG. 1, bottle 17 is shown at or near the exit position from table 26 and cap 15 would be seated on bottle 17 with a torque determined by the slip clutch of a spinning capping head 80 shown in dashed lines with a spin rotational direction shown by arrow 81. Bottles exit from the capping machine by virtue of an exit star wheel or other means receiving the bottles from the rotating table, such as table 26, and delivering them to a conveyor, in a manner which is generally the reverse of their mode of entry (e.g. by an entry star wheel operation which delivers from conveyor to rotating table).
Thus, it may be seen that these prior art patents are very limited in their teaching and utilization, and an improved lifter ring rotation control is needed to overcome these limitations.